This can be a very broad question and as such I can only give a broad answer 🙂
Probably the easiest non-vr way would be to create you UI the way you want using Unity UI component (buttons, sliders, etc), and then have FC listen to UI events, using the nodes found under the “Events/Object/UI” category (for example UI Button, UI Slider, UI Dropdown etc), then connect nodes together for what you want to happen when those events take place (button clicked, slider value changed, new option selected etc).
With that said, when it comes to vr UI, you will of course need a way to interact with those UI controls via the “vr joysticks”. As far as I remember, there are libraries (even unity ones) that pretty much set this up for you (the vr joysticks) and thus be able to interact with the UI with those vr joysticks. Creating or recreating the vr joysticks is better done with code, or of course an existing library. FC being an event driven system, is better used to “listen” to the UI controls like explained above and connect “what happens” accordingly.
Please let me know if this helps or if I can help you further in any way.