Since you're willing to edit the directive's source, you can inject your own Angular $emit inside of its own internal onMove handler:
// emit 'onMove' up the scope chain
scope.$emit('move');
Then, assuming your controller's scope is the parent of the directive, you can just insert the following into the controller:
$scope.$on('move', function(){
console.log("move fired");
});
You might consider debouncing the event handling a bit to avoid excessive responses to the event - whether or not that's useful for you depends on what you're doing.