How does a person know if his Android phone is hacked, being tracked or spied on?
Android phones are majorly tracked using some service that runs in your device in background and it continues to run all the time, I would highly suggest you to check all running applications periodically if you notice something running without your consent which is not a part of system applications that may be a service tracking your device.
Or there is an easy way also, install an antivirus it will let you know what all applications are running in background indefinitely.
Basically you have to look for something unusual.
but there is one more thing that can be done to the device without the user knowing it, that is sim tracking. It is difficult to know, for that there is not much you can do. If somehow you know your sim is being tracked then put your call duration to 59 seconds, most people are interested in longer calls, so they record your calls and only bother about the ones that are longer in time.
One last thing, you can use wifi calling if you feel your sim is being tracked.
If you feel that this is not going to help you, try reaching out to cyber cell, they will bust the guy in seconds.