Apple Watch does have a remote control feature, intended for controlling the watch from your phone, as part of the accessibility options. It's certainly technically possible that this feature is being abused to get access to data that would otherwise be locked down by Apple's strict sandbox post-exploitation.
Or, more likely, it's some kind of shitty prank by someone nearby to the users.
Or, more likely, it's some kind of shitty prank by someone nearby to the users.