try this-

    remove_meta_box(\'categorydiv\');
add_meta_box(\'categorydiv\', "Categories", \'mycustom_category_meta_box\', null, \'side\', \'core\', array( \'taxonomy\' => \'category\' ));
function mycustom_category_meta_box($post, $box) {
    $defaults = array(\'taxonomy\' => \'category\');
    if ( !isset($box[\'args\']) || !is_array($box[\'args\']) )
        $args = array();
    else
        $args = $box[\'args\'];
    extract( wp_parse_args($args, $defaults), EXTR_SKIP );
    $tax = get_taxonomy($taxonomy);

    ?>
    <div id="taxonomy-<?php echo $taxonomy; ?>" class="categorydiv">
        <ul id="<?php echo $taxonomy; ?>-tabs" class="category-tabs">
            <li class="tabs"><a href="#<?php echo $taxonomy; ?>-all" tabindex="3"><?php echo $tax->labels->all_items; ?></a></li>
            <li class="hide-if-no-js"><a href="#<?php echo $taxonomy; ?>-pop" tabindex="3"><?php _e( \'Most Used\' ); ?></a></li>
        </ul>

        <div id="<?php echo $taxonomy; ?>-pop" class="tabs-panel" style="display: none;">
            <ul id="<?php echo $taxonomy; ?>checklist-pop" class="categorychecklist form-no-clear" >
                <?php $popular_ids = wp_popular_terms_checklist($taxonomy); ?>
            </ul>
        </div>

        <div id="<?php echo $taxonomy; ?>-all" class="tabs-panel">
            <?php
            $name = ( $taxonomy == \'category\' ) ? \'post_category\' : \'tax_input[\' . $taxonomy . \']\';
            echo "<input type=\'hidden\' name=\'{$name}[]\' value=\'0\' />"; // Allows for an empty term set to be sent. 0 is an invalid Term ID and will be ignored by empty() checks.
            ?>
            <ul id="<?php echo $taxonomy; ?>checklist" class="list:<?php echo $taxonomy?> categorychecklist form-no-clear">
<li class="popular-category" style="float: right;">
<label class="selectit">
<input type="checkbox" name="" class="category-check-all" onchange="jQuery(this).closest(\'ul\').find(\'input[type=\\\'checkbox\\\']\').prop(\'checked\', jQuery(this).is(\':checked\'));">CHECK ALL
</label>
</li>
                <?php wp_terms_checklist($post->ID, array( \'taxonomy\' => $taxonomy, \'popular_cats\' => $popular_ids ) ) ?>
            </ul>
        </div>
    <?php if ( current_user_can($tax->cap->edit_terms) ) : ?>
            <div id="<?php echo $taxonomy; ?>-adder" class="wp-hidden-children">
                <h4>
                    <a id="<?php echo $taxonomy; ?>-add-toggle" href="#<?php echo $taxonomy; ?>-add" class="hide-if-no-js" tabindex="3">
                        <?php
                            /* translators: %s: add new taxonomy label */
                            printf( __( \'+ %s\' ), $tax->labels->add_new_item );
                        ?>
                    </a>
                </h4>
                <p id="<?php echo $taxonomy; ?>-add" class="category-add wp-hidden-child">
                    <label class="screen-reader-text" for="new<?php echo $taxonomy; ?>"><?php echo $tax->labels->add_new_item; ?></label>
                    <input type="text" name="new<?php echo $taxonomy; ?>" id="new<?php echo $taxonomy; ?>" class="form-required form-input-tip" value="<?php echo esc_attr( $tax->labels->new_item_name ); ?>" tabindex="3" aria-required="true"/>
                    <label class="screen-reader-text" for="new<?php echo $taxonomy; ?>_parent">
                        <?php echo $tax->labels->parent_item_colon; ?>
                    </label>
                    <?php wp_dropdown_categories( array( \'taxonomy\' => $taxonomy, \'hide_empty\' => 0, \'name\' => \'new\'.$taxonomy.\'_parent\', \'orderby\' => \'name\', \'hierarchical\' => 1, \'show_option_none\' => \'&mdash; \' . $tax->labels->parent_item . \' &mdash;\', \'tab_index\' => 3 ) ); ?>
                    <input type="button" id="<?php echo $taxonomy; ?>-add-submit" class="add:<?php echo $taxonomy ?>checklist:<?php echo $taxonomy ?>-add button category-add-submit" value="<?php echo esc_attr( $tax->labels->add_new_item ); ?>" tabindex="3" />
                    <?php wp_nonce_field( \'add-\'.$taxonomy, \'_ajax_nonce-add-\'.$taxonomy, false ); ?>
                    <span id="<?php echo $taxonomy; ?>-ajax-response"></span>
                </p>
            </div>
        <?php endif; ?>
    </div>
    <?php
}