Untitled

add_action('salesking_customers_custom_columns_header', function(){
	?>
	<th class="nk-tb-col tb-col-md"><span class="sub-text"><?php esc_html_e('Custom User Field','salesking'); ?></span></th>
	<?php
});

add_action('salesking_customers_custom_columns_content', function($customerobj){
	?>
	<td class="nk-tb-col tb-col-md">
	        <span class="tb-amount"><?php echo get_user_meta($customerobj->get_id(),'custom_meta_key', true); ?></span>
	    </div>
	</td>
	<?php
}, 10, 1);