How to get category for product page? | WooCommerce

A WC product may belong to none, one or more WC categories. Supposing you just want to get one WC category id.

There are two parameters of get_the_terms function.

global $post;
$terms = get_the_terms( $post->ID, 'product_cat' );
foreach ($terms as $term) {
 $product_cat_id = $term->term_id;
 break;
}