Add script to thank you page in woocommerce.

woocommerce_add_script_to_thankyou.php

<?php

add_action( 'woocommerce_thankyou', 'my_custom_tracking' );

function my_custom_tracking( $order_id ) {

// Lets grab the order
$order = new WC_Order( $order_id );

/**
 * Put your tracking code here
 * You can get the order total etc e.g. $order->get_order_total();
 **/

}

?>