That time you can create your custom drop-down with search functionality

For that first add JS and CSS file into your project. you can find js & CSS file from here custom-dropsown.

After Download that Code you can add that references in you page.

and put that code in your script file

$(document).ready(function () {
$.ajax({
url: ‘your url to get data’,
dataType: ‘json’,
success: function (data) {
var ddlValue = new Array(); // create array
$.each(data, function (index, item) {
ddlValue.push(item);
});
$(“#ddluserId”).select2({
data: ddlValue
});
}
});
});