您需要使用get_the_terms() 要获取与帖子相关联的分类术语，并在其中循环，直到找到一个具有图像集的术语：

$post.     = get_queried_object();
$terms.    = get_the_terms( $post, \'taxonomy_name_here\' );
$image_url = null;

if ( $terms && ! is_wp_error( $terms ) ) {
    foreach ( $terms as $term ) {
        $attachment_id = get_term_meta( $term->term_id, \'category-image\', true );

        if ( $attachment_id ) {
             $image_url = wp_get_attachment_image_url( $attachment_id, \'full\' );
             break;
        }
    }
}

if ( $image_url ) {
    // Output image as needed.
}