Either use the database polling thread
https://tango-controls.readthedocs.io/en/latest/tutorials-and-howtos/how-tos/how-to-pytango.html#events
or use explicit event pushing
https://tango-controls.readthedocs.io/en/latest/development/device-api/generating-events.html?highlight=push%20event#generating-events-in-a-device-server