During the iOS 9 public beta, take the following steps to prevent updates to iOS 9 public beta or monitor whether devices are using iOS 9 public beta:
- Prevent installation of iOS 9 public beta on Supervised devices by installing an iOS restriction profile that prevents manual profile installation. More information can be found here: https://support.apple.com/en-us/HT204444
- Create a compliance policy and notify the administrator if any devices are running a version that is higher than iOS 8.4.0.
- Run a device MDM detail report.