acf-post-object.php

<?php $post_object = get_field('post_object');
if( $post_object ):     // override $post     

$post = $post_object;    
setup_postdata( $post );     ?>    
<div>        
  <h3><a href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h3>        
  <span>Post Object Custom Field: <?php the_field('field_name'); ?></span>   
</div>    
<?php wp_reset_postdata(); // IMPORTANT - reset the $post object so the rest of the page works correctly ?>

<?php endif; ?>