Get Yoast SEO primary category

yaost-primary-category.php

<?php
		/**
		 * Gets Yoast SEO primary category.
		 *
		 * @param int $post_id ID of the product to get category of.
		 * @return string
		 */
		public function get_primary_cat( $post_id ) {
			$cat_name = '';
			if ( class_exists( 'WPSEO_Primary_Term' ) ) {

				$primary_cat_id = get_post_meta( $post_id, '_yoast_wpseo_primary_product_cat', true );

				if ( $primary_cat_id ) {
					$product_cat = get_term( $primary_cat_id, 'product_cat' );
					if ( isset( $product_cat->name ) ) {
						$cat_name = $product_cat->name;
					}
				}

			}
			return $cat_name;
		}