If you have build the Intruder detection system using a push button, then you can attach the push button such that the button gets pressed soon as the door is opened or when the intruder steps in front of the door etc.

Also, important thing to note is while configuring the alerts, you have to make sure to set the condition as follows:

• if 1 is equal to 1:

The reason we do this is because the circuit connections we made for the push button will send a HIGH to the Digital pin 1 of the Bolt module when the button is pressed.