Tracking a person without their knowledge is a criminal offence in the UK
What to look for if you think you are being tracked. It may be a spouse with a suspicion of an affair or a employer who thinks their employee is moonlighting, whatever the scenario tracking a person without their consent is a serious offence covered by the Protection of Freedoms Act 2012.
How can I find out if I am being tracked? I is likely that a magnetic tracking device would be used as these devices are easy to hide and have no wires or antennas making them very easy to conceal. They would normally be placed inside the vehicle if the stalker has access or underneath the vehicle if not.
There is no easy way to detect a GPS tracking device but the person tracking will almost certainly have incriminating evidence on their phone or PC. They will either have text messages from the tracker including google map links or will have an app that will show the tracker location and route history.
If you think you may be a victim of stalking you can report it or get more advice here