Recording ring placement on excel

Hello. I am just beginning to work on a project and need a little direction.

I am working on an old kids game called tower of Hanoi. It is where three or more rings of different sizes are place on one of three pegs. Moving one ring at a time, and never putting a bigger ring on a smaller, the player needs to move all rings from one end to the other.

I would like to record each movement to an excel sheet. Ex: ring A to peg 3, so the move would be A3.

What would be the best way to identify each ring so the arduino could sense the placement even if there is already a ring there?
Ex: peg 1 has ring B and C, the ring A is moved back. Even though there are three rings on peg 1 the move should just record A1.

I dont mind doing research, I would just need a direction.
Thanks for any help you guys can give!

Is it allowed to let the ring being moved pass some kind of detector before being dropped down on the new pin?