use this function to get the points earned in a single order.

functions.php

<?php

function get_total_user_point( $order ) {

 $user_id = false;
 if ( !$order instanceof WC_Order ) {
 $order = wc_get_order( $order );
   }

 $user_id = $order->get_user_id();
 if( $user_id ){

 $points = get_user_meta( $user_id , '_ywpar_user_total_points', true );

 return $points;
   }
 return '';

}

echo get_total_user_point( ORDER_ID );