How to find out the Ubiquiti Unifi AP and switch serial number?

This note mentions how to learn the serial number in Ubiquiti Unifi access points.

There is no field on the panel where we manage Ubiquiiti devices that shows the serial number of access points. To access this information, we need to connect to the device with SSH and run the following code. SSH information can be found on the panel from the Settings > System > Application Configuration > Device SSH Authentication menu.

grep serialno /proc/ubnthal/system.info

When we run the code, we see that the serial number of the devices is the MAC address.