Ingame slider for light control

How do I create an ingame slider to control the sun within my scene?

I would like to know how is it possible to create a menu (slider/controller) whithin my scene to control the sun & moon motion? I would like to have that slider so the user could set the sun position by himself meaning that the sun won’t be moving by the default settings.

In this video it is shown how to set the sun but it doesn’t say anything about the possibility to create a controller for it - YouTube

It should be played on an iPad.

Would you be able to help us with this issue?