Get meta data from JetEngine relations from the code

get-realtion-meta.php

<?php
$rel_id     = 111; // Set here your actual Relation ID. You can get it from an address bar on relation settings edit page
$relation   = jet_engine()->relations->get_active_relations( $rel_id );
$parent_id  = 111; // ID of prequired arent object from relation
$child_id   = 111; // ID of prequired arent object from relation
$key        = 'meta_key'; // Name/ID of meta field to get
$meta_value = $relation->get_meta( $parent_id, $child_id, $key );