I don't think you can use a phone to monitor your computer temps because I don't think anyone has made an app for a computer to send that information to the phone, i'm not positive on that though. You can use CPUID which shows current, max and min temps of most things inside the case. Or use msiafterburner with riva tuner statistics which can monitor things like gpu temp and other stats while in games and things like that and it displays it in the corner of the screen.