use Nette\Application\UI\Form;

public function createComponentForm()
{
    $form = new Form();
    
    $form->addCaptcha('captcha', 'Are you robot?');
    
    $form->addSubmit('send');
    
    $form->onSuccess[] = function (Form $form) {
        dump($form['captcha']);
    };
    
    return $form;
}