Sweeping for spy trackers depends on whether you think people have had access to your home. For instance, if your landlord has a key to your apartment, then it's worth checking every couple of weeks.
Remember, these days, it's less likely that actual devices are installed and more common for wifi connected equipment to be hacked. For instance, some smart TVs are fitted with microphones and cameras. Consult the manual or contact the manufacturer to find out how to disable them. Think twice about purchasing any smart home devices, such as the Amazon Echo or Google Home if you are already a target of stalking and spying.