Q1. Why i don’t receive mobile message when i put the sensor cable in/out of the water? 

You can check:

1. The time range is about 8s-15s depend on the wifi network, it exists delay if the wifi network is not good.

2. Please better try with running water.

Q2. Why i can not hear the alarm when i put the sensor cable in/out of the water?

Firstly, please check the setting in your mobile, select Notification, and find the App, and slide on in the notification. Secondly, make sure you have slide on in the alarm of the APP.