I am looking to add a custom device property to the devices managed using intune. Intune currently has only a specific set of device properties which are read from the device. I have tried to update the property as device name, but that is not editable.
I'm afraid you cannot add custom device property in Intune StandAlone. However, when you integrated Intune with ConfigMgr (the Intune hybrid), you will be able to enable collecting more device properties by adding the hardware inventory classes for mobile devices(IOS, Andorid, WinPhone,etc). More details can be found here.