https://techcrunch.com/2019/05/14/amazon-rolls-out-alexa-guard-to-help-protect-your-home-while-youre-out/

Amazon announced this morning that it’s begun to roll out Alexa Guard to all Echo customers in the U.S. The feature lets the company’s line of smart home products double as home security devices while the user is out. Say “Alexa, I’m leaving” on your way out the door, and the Echo device will start listening.

The key feature here is something called “Smart Alerts,” which listen for key sounds, indulging breaking glass and smoke and carbon monoxide alarms. If the Echo hears the noise, it will send you an alert, coupled with an audio recording of noise.