After having entered the Passport Nr. / Date of birth / Date of expiry place your smartphone on the inner cover of your passport. Try both the front and the back until a progress bar appears. After some seconds you will see your name and your picture appear on the screen.
The app does not communicate your private information to any third party. Only technical information about the passport are collected to help improve UBIC (https://ubic.app)
The app is open source: https://github.com/rgex/bondi-android-passport-reader