Detect change of state on input

Hello,

I've been lurking around, searching, trying to find some info on detecting change of state and using that to trigger my MyController rules.
I have a steel framed house, and it's a nightmare to run new wiring in the walls, so I was hoping to utilise the existing light switches and detect the change of state (from OPEN to GROUND) on the MEGA.
If any of you fine people have done this or something similar, I'd love to hear from you, or if anyone knows of some further reading, I'd appreciate if you could point me in the right direction.

Thanks
Please help

I didn't find the right solution from the Internet


References:
forum.mysensors.org/fdgd/detect-change-of-state-on-input
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