Wifi or remote room monitoring solutions.

To clarify the title, I'm in need of finding a solution for tracking entry into a condo unit in another state.

We have a condo that is used semi-regularly; but there are periods of time it is vacant. We have a commercial door code lock on the unit so that we don't have to always worry about losing the key. The problem this creates is that we have reason to believe that the cleaning crew may be accessing the unit and staying overnight when none of us are there. They are made aware of arrival and departure dates for freshening up the place prior to a visit and cleaning post visit.

We have not added wifi to the unit yet since we (several families own unit) try to keep the kids outdoors while there, but we are thinking it may allow us to solve this remote monitoring issues. We currently lease the condo complex wifi on a weekly or monthly basis while there. We really don't want cameras there, but are looking for something that sends alerts or tracks door opening/ closing or noise in the unit. A portable camera we can set out when we leave may also work if it's motion activated to send an alert and then can be viewed remotely.

Would rather not replace keypad door lock with a wifi one, since we have $300-$500 in this one already.

I'm thinking a wifi noise monitor that we can activate and deactivate may be best. I found THIS ONE , but the reviews aren't the best. Anyone know of anything similar that they have good experiments me with? Or maybe something that just tracks, alerts and logs door opening and closings? A non-wifi old school logging type of device whisk work to, but I figure we'll likely have to establish our own wifi to get the tracking we need.

Sorry so detailed.

TIA