Is it possible to trigger an Ajax CallBack Function After a Link is Click
Yeah you just need to use use-ajax class for this.

$form['myid_print']['myid_print_search_idnumber_wrapper'] = array(
  '#type' =&gt; 'item',              
  '#markup' =&gt; l(t('Test Ajax'), 'admin/ajax-url/nojs', array('attributes' =&gt; array('class' =&gt; 'use-ajax'))),
); 


Checkout this blog : http://www.computerminds.co.uk/drupal-code/make-link-use-ajax-drupal-7-its-easy.