Here is a smart sensor that you can install anywhere to get temperature readings on your smartphone. ThermoPeanut connects to your iOS or Android smartphone via Bluetooth. You can check current temperature and view history any time. When the temperature is outside the desired range, you get a notification on your phone. ThermoPeanut also sounds an audible alarm.
The thermometer is compatible with Nest and IFTTT. It can be linked to multiple smartphones and tablets. The battery lasts up to 6 months.[where to get it]