Thanks everyone for your help, I think I should elaborate slightly - feel free to tell me this doesn't exist at this point.
I don't ride bikes and know very little of them but I'm working on a museum exhibit for a certain UK racetrack which demonstrates what happens when you press your brake lever. So think spinning disc - squeeze lever - callipers close and disc slows down, an indication showing speed and temperature of disc is shown. Keep in mind this is all fabricated and is just showing the core principle of a brake system there are no hydraulics or anything. So what I thought the easiest thing to do would be to take the cables that would run to activate your brake lights and use them to send a signal to our control box which in turn closes the callipers etc. But because this is open to the public we don't like to have exposed switches and cabling.
I found an image of one where the microswitch had been sealed in an enclosure on the brake lever, the problem I with this is it's from Wish.com. So I might get what I want or I might end up with half a donut. I've added an image of the ones I found. What are the chances of me finding something like that from a reputable resaler.
Thanks again.