In addition to Erel's advice...
When do you want the notification?
If not in real time then you can poll the location lat lon .
Another solution is to receive continuous signal from the device by bluetooth, but this is good for about 10 meters (the range of bt) after 10 meters the signal will be lost. The workaround will be to shield the BT to control its sensitivity to the level you want, so it can be lost after 5 meters.
hello,
I would like to check in real time the position and if it exceeds the meter set alerts me with a sound.
I would also create a small radar to identify the object is possible?