can you recommend any (opensource or trusted) android apps to check who’s using your wifi? or any cmd prompt code to search on the desktop?
a small doubt: can anyone hack your computer through WiFi? If so, How to prevent that (or) How to take measures after you think you been hacked?
Login to your router or wireless access point and check what devices are connected. Then setup mac adress filtering to improve your security, if you can be bothered to have to add your devices mac adresses manually.
mac adresses are easily spoofed though, so it isn’t foolproof.
Also note that mac addresses can change automatically on iOS, because of the Private Wifi Address feature
Same on Android, though the default is a random MAC per network/ssid