You have two options:
The first one is to have a custom button with a template.
The second one is to have a regular controlType: ‘button’, but add a unique cssClass and after that get the element and add an eventListener.

Here is a demo in which the two options are shown:  https://codepen.io/svetoslavb04/pen/PoePJdM

Hope this helps and if you need further help, do not hesitate to contact us!

Best Regards,
Svetoslav Borislavov

Smart UI Team