User.php

<?php
class User
{
    public function getThis()
    {
        return $this;
    }

    public function setThis($that)
    {
    }
}

UserType.php

<?php
class UserType extends \Symfony\Component\Form\AbstractType
{
    public function buildForm(\Symfony\Component\Form\FormBuilderInterface $builder, array $options)
    {
        $builder->add('name', CompoundType::class, [
            'property_path' => 'this'
        ]);
    }
}