We have designed a door alarm which will trigger as soon as the door(s) being watched is opened. The way we set this up is by using an ESP32 wired with a Sonar Sensor to watch the readings from above the door looking downwards. Once the alarm is set, it will be reading the distance from the top of the doorframe, down to the floor. This height is an average of 200cm. In order to give it some buffer room to not go off if something small happens to just walk by, we set the sonar to send "on" to the webspace if the sonar has detected something less than 150cm away. Now, a second ESP32 connected to a 5v Speaker is placed in a location in which you can hear it. this ESP32 is constantly reloading the webspace, looking for that "on" to be posted. As soon as it refreshes, and sees "on" it will beep a constant note 16 times (tone and count may be increased with ease).