<div class="input-group">
  <input type="text" class="form-control datepicker" />
    <div class="input-group-append">
      <button type="button" class="btn btn-outline-secondary" data-toggle="datepicker"><i class="far fa-calendar-alt"></i></button>
    </div>
</div>

jQuery('input.datepicker').datepicker();