ApiController.php

public function actionGetModel()
    {
        $model              = new ContactForm();
        $captcha            = new Captcha();
        $captcha->model     = $model;
        $captcha->attribute = 'verifyCode';
        $cview              = $captcha->getView();
        $response           = new Response();
        $response->format   = Response::FORMAT_JSON;
        //        $response->data['message'] = "ContactForm";
        $response->content = Json::encode(
            [
                'attributes' => $model->attributes,
                'validation' => $model->activeValidators,
                'rules'      => $model->rules(),
                'labels'     => $model->attributeLabels(),
                'captcha'    => $cview
            ]
        );
        $response->setStatusCode(200);
        \Yii::$app->end(0, $response);
    }