A pocket watch that not only reads time but tracks whether you’re physically being followed with acts of suspicion accurately tracked and straight away ping’ed into local police “to watch list” as the radar hits the specs and parameters of definitely being followed with ability to track if it’s by an armed or unarmed person. 

Self alerting linked to police. This app already exists. True or False. 

Whether it’s true or not in existence does not matter. How and when would you use such an app and for what thought, scenario or concern you have in mind?