There are several lengthy and informative threads on hive security if you have a look using the search function, some ideas are very entertaining, a few are lllegal and some are very sensible but the reality is that, if you have an out apiary anywhere accessible, it's going to be vulnerable to a determined thief.
The general concensus was:
A> Site your apiary where it cannot be seen from a road or a public path.
B> Employ some means of making it difficult to remove the hives .. fastening them to a strong point set in the ground perhaps.
C> Mark all the components in a permanent and clear way.
D> If people live near your out apiary then make sure they have your contact details and get a jar of honey or two in return for keeping their eyes open.
E> Real or fake CCTV cameras can be a deterrent
Anything that shuts the door after the horse has bolted is probably a waste of time as the Police seem to have little success in finding stolen bees/hives. Unless you live close enough to respond to a call then any monitoring devices that registers when the hive is disturbed will be a waste of money.
But .. as I said earlier, it's a sad fact that a determined thief will circumvent all of these and it's sadder that the vast majority of hive thefts are clearly carried out BY BEEKEEPERS - so keep your apiary locations to yourself !