I gave a first answer, but it turned out to be wrong so I deleted it.
The answer to this is really complicated.
You can detect some I beacons with some android watches. But none of them work perfectly and a lot of them require that you be really close to the Beacon, within about a meter.
Pebble tried to do this back in 2014, but it just turned out to be too hard on the battery life and they dropped the Detection feature for the pebble time.
There is also an ongoing problem that if you kill the app on the watch you may have problems restarting it again. Different watches handle this differently so you may just have to experiment.
And the biggest problem of all is that using an IBeacon Detection app can kill the watch battery really quickly.
There are IBeacons which can be worn and work very well, but then you need to have a phone or tablet plugged in in the stationary location to act as the detection station. This is what we do at my house. I have a Beacon on my wheelchair and we have a tablet on each side of the house which acts as a home automation dashboard and also has the Beecon + app (iOS only).
So there are two separate problems that you’ll run into. The first is the distance at which the Beacon can be detected. Many people who have tried using a watch as the receiving station have found that it only works reliably when the distance is within One or 2 m. That’s OK for touchless switches, but not for micro location.
The second issue is battery life for the receiving station device. If this is a watch, you can kill the battery life very quickly. So it’s not something that you would use all day long.
The following is a detailed project report of somebody who tried to write a detection app on a smart watch and details the problems they ran into, in particular distance:
Estimote, One of the biggest IBeacon manufacturers (very Nice products, these are the beacons that I use), says that their android SDK will work on an android wear watch, but that still doesn’t address the distance or power usage issues.
So you can do this as far as detecting one beacon one time at a short distance. But whether it would meet your practical requirements just depends on the details of what you’re trying to accomplish.
At my house, I use the Beecon plus App on my watch, but the detection is being done by an iOS phone or tablet and the watch is just getting the information from that. And the beacon is what’s moving around. As I mentioned, I have a beacon on my wheelchair and my housemate has one in his backpack. Mine is used for zone detection inside the house, his is just used for “home” and “away.”