About cameras in Rift S headset and unity

Hi! before asking, im sorry for my bad english (im from Spain) and im also new working with Unity for Oculus. 
The point is, we have an Oculus Rift S, and we are working in our own project created in Unity, we want to use the cameras from the headset along with our project (change the background from unity to image from oculus's cameras, something similar to the popup menu from oculus store...) but we dont know how to configure them in the unity project or even if we can do it...

Thanks in advance for any help or guide you can provide.