Active Field

<?= $form->field($site, 'phone_1', ['template' => "{label}\n<div class=\"col-lg-3\">" . Html::dropDownList('phone_comment_1', 0, ArrayHelper::map( PhoneComment::find()->all(), 'id', 'name'), ['class' => 'form-control b-right'] ) . "{input}</div>\n<div class=\"col-lg-7\">{error}</div>", 'inputOptions' => ['class' => 'form-control b-left', 'id' => 'phone_1']]) ?>

Источник

https://github.com/yiisoft/yii2/blob/master/framework/widgets/ActiveField.php#L155