<?php

use wdmg\widgets\ReCaptcha;
...

$form = ActiveForm::begin();
...
echo $form->field($model, 'userVerify')->widget(\wdmg\widgets\ReCaptcha::class, [
    'language' => 'uk-UA',
    'siteKey' => '_your_site_key_',
    'callbacks' => [
        'onload' => 'console.log("ReCaptcha: onload")',
        'success' => 'console.log("ReCaptcha: success")',
        'expired' => 'console.log("ReCaptcha: expired")',
        'error' => 'console.log("ReCaptcha: error")'
    ],
    'widgetOptions' => [
        'class' => 'pull-right'
    ]
]);
...
ActiveForm::end();

?>

<?php

use wdmg\validators\ReCaptchaValidator;
...

/**
 * @return array the validation rules.
 */
public function rules()
{
    return [
        ...
        ['userVerify', ReCaptchaValidator::class, 'secretKey' => '_your_secret_key_', 'message' => 'Please confirm that you are not a robot.'],
        ...
    ];
}

?>