The selfie stick is recognized by the system as a headset with a remote control, so you can use it to control the camera. Often everything starts working without any prior configuration. But if you can't take a picture, then you need to go to the camera settings, find the settings for the volume keys and activate the picture function by pressing the key.
In the camera settings, activate the sound key, by pressing which you can shoot and everything worked out. In my phone, this function was already set by default. In Lenovo, by 5 I could not cope with this problem and threw this barbell into the box, and with the new phone HUAWEI P smart Z is out.