Bluetooth can be 2 ways. But can the implanted device transmit far enough to be picked up by another device or to pick up the sound you are trying to send? Maybe...
As far as how to work it, many of these exams are standardized with a set number of questions. Let's say there are 1000 questions all together and you get tested on 100 of the 1000. You can work out a system where you can get the answers with minimum transmission to your confederate.
It's a lot of work. It seems easier to just study.
One of my economics teacher used to let us fill an index card with information for our exams. We could handwrite as much as we wanted and look at it as much as we needed. So every exam everyone had their card at hand. We would all brag about how small we were able to write. We had to do so much reading and writing to fill up the card that a lot of it stuck in our brain and we hardly needed it. It turned out to be the way he got his students to study. Pretty smart...