detecting when user inserts mini headphone jack?

Hi - I'm in the "pondering" stages of a new sound installation project. I would like to be able to use mini headphones jacks as a 'switch' so that I can monitor the state of each jack, along with providing an audio signal through the jacks.

None of the jacks I have in my catch all parts box have a built-in make/break feature for when a jack is inserted/removed. Do such jacks exist or is there some simple circuitry I can add?

Maybe a simple question....

Do such jacks exist

Yes - I don't have any jacks without this feature I thought they all had it.

Typically, those jacks have a "switch" (or two for stereo) that connects the tip (and ring) to an additional contact on the jack when there's no plug inserted. So, e.g., you can wire that other contact to the internal speaker, and have it automatically disconnected when you plug in the headphones.

I don't know of any with a separate "plug inserted" switch, but there might well be some out there. Another possibility, if your audio is mono, would be to use a stereo jack, and use the ring contact for a "jack present" switch.