Custom field for woocommerce product

functions.php

/**
 * Create Custom Members Price Field for Woocommerce Product
 * @since 1.0.0
 */
function nb_create_member_price_field() {
	$args = array(
		'id' => 'member_price',
		'label' => __( 'Members Price', 'cfwc' ),
		'class' => 'nb-custom-field',
		'desc_tip' => true,
		'description' => __( 'The price for members.', 'rider-ways' ),
	);
	woocommerce_wp_text_input( $args );
}
add_action( 'woocommerce_product_options_general_product_data', 'nb_create_member_price_field' );
/**
 * Save Custom Members Price Field for Woocommerce Product
 * @since 1.0.0
 */
function nb_save_custom_field( $post_id ) {
	$product = wc_get_product( $post_id );
	$title = isset( $_POST['member_price'] ) ? $_POST['member_price'] : '';
	$product->update_meta_data( 'member_price', sanitize_text_field( $title ) );
	$product->save();
}
add_action( 'woocommerce_process_product_meta', 'nb_save_custom_field' );