Android 7.0 Nougat update has started hitting Motorola Moto Z in China, bringing a new build version NCC25.106-11. Currently, the update is only hitting units in China.
The new update will make Moto Z devices compatible with Google's Android powered VR platform Daydream. Incase you are not aware, the update came months ago after the company officially announced the global roll out of the update.
The update just started rolling out, and may take little time for the update to arrive on your phone via OTA. But if you feel impatient, you can manually check for the update by heading to your phone's Settings => About Phone => System update.