php - Select2 dropdown with dynamic name and image in yii2

I am working on yii2.

I have form with many fields.

I have one field that which has name and image.

I want to display that with select2 dropdown with name and image. Name is coming but how to display image in that dropdown.

Yii view file code :

<?php $form = ActiveForm::begin(); ?>
       <div class="col-xs-6 col-md-5">
          <?= $form->field($model,'db_fieldname')->dropDownList(['0'=>'Select category']
          + ArrayHelper::map(Category::find()->all(),'id','name'),
          ['multiple'=>'multiple']) ?>
       </div>
<?php ActiveForm::end(); ?>
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I have wrote JS : At the end of my view file

<?php
    $this->registerJs('$("select").select2( templateResult: format);');
 ?>
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Now according to above code please guide me how to display image in dropdown.