I need to add search box inside the select tag with ng-option.
<select class="form-control" ng-model="modelname" ng-options="category.id as category.name for category in Categories ng-change="getSubCategory()">
<option><--search box should be here--></option>
You can't with standard html. You'll have to create something custom - something along these lines.
<ul class="custom-select"> <li class="custom-select__option" ng-repeat="$ctrl.options"><input type="search"/></li> <ul>
It won't be hard to create, but that's the direction you'll need to go.