Example of how to use the .on formSubmit listener.

formSubmit.js

<script>
    jQuery( document ).ready( function() {
        //Setup our on formSumbit Listener. 
        jQuery( document ).on( 'nfFormSubmitResponse', function() {
            //Do Stuff
            ga('send', 'event', 'Email List', 'Subscribed', 'New Subscriber');
         });
    });
</script>

use simple if condition, to use form title as event label.

<script>
jQuery(document).ready(function(){
jQuery(document).on('nfFormSubmitResponse', function(event, response, id){
if(response.id == '2'){
ga('create', 'UA-**********-*', {'name': 'gaCode'}); // optional in case if you need to specify the tracker.
ga('gaCode.send', 'event', 'NF submissions', 'Form Submitted', 'Enquire');
}
});
});