Yes, Apple watches are hackable. There have been a few reported cases of hackers gaining access to people's Apple watches and using them to spy on their owners or steal sensitive information. In one case, a hacker was able to remotely view and record audio and video footage from an unsuspecting victim's Apple watch.
While the number of reported hacks is relatively small, it's important to be aware that these devices are vulnerable to attack. If you own an Apple watch, take steps to protect it by setting a strong passcode and avoiding downloading apps from unknown sources.