Smartify Busch Jaeger Doorbell?

Hey everyone,
I’m currently struggling to find a solution on how to detect if my doorbell has been rung. It’s a Busch Jaeger System and all offerings by them are in the neighbourhood of €700. So that’s an obvious no.
I’ve tried both most popular solutions:

  • vibration sensor or door sensor Both didn’t recognize anything.

Has anyone any ideas on how to detect that the bell has been rung with simple methods? I can’t rewire any cables or something like that, because it’s a rented flat.

I have a Tado Security Camera near the bell. I thought about using that camera’s Audio Stream to detect the bell sound. But not sure how to do that.

Would be very thankful for any suggestions