add this shortcode to yourtheme/functions.php or snippets code with change your meta key

function custom_op_barcode_key_setting($fields){
     $fields['_barcode'] = "WooCommerce Barcode"; // change _barcode to your meta key
     return $fields;
 }
 add_filter( 'op_barcode_key_setting', 'custom_op_barcode_key_setting' ,10,1);