Laravel 5 jquery post request not working

Hi I'm trying to get data via ajax for laravel. This is my code. Controller,

public function findByAjaxCode(Request $request)
    {
        return $request->crime_code;
    }
}

Jquery,

$('.serch_crime_by_code').click(function(e){
                e.preventDefault();
                $.post( "/admin/find_crime_by_ajax", { crime_code: $('crime_code').val() }, function(data){
                    alert(data);
                });
            });

Form,

<form class="form-edit-add find_crime" role="form" method="POST" enctype="multipart/form-data">
            <!-- PUT Method if we are editing -->

                    
<div class="form-group">
                                <label class="control-label" for="name">Enter crime code</label>
                                <input type="text" class="form-control crime_code" id="crime_code" name="crime_code"placeholder="Crime code" value="">
                            </div>

                             <button type="submit" class="btn btn-primary pull-right serch_crime_by_code" v-on:click='searchCrime'>
                                 
                            </button>
</form>

But I'm only getting empty result for alert always...

via Chebli Mohamed