- Form createForm(string|FormTypeInterface $type, mixed $data = null,
array $options = array())
- FormBuilder createFormBuilder(mixed $data = null, array $options = array())
You can "customize" Event of the process of Form component with a Form Event compatible with Event Dispatcher Component.
Symfony Docs :
The Form component provides a structured process to let you customize your forms, by making use of the EventDispatcher component. Using form events, you may modify information or fields at different steps of the workflow: from the population of the form to the submission of the data from the request.