Custom Woocommerce hook

Create a custom Woocommerce hook with which I can call with the following function:

if ( function_exists( 'wc_st_add_tracking_number' ) ) {
wc_st_add_tracking_number( $order_id, $tracking_number, $provider, $date_shipped, $custom_url );
}

The result is that I can use this hook for the order completed email in WC