1. You can give them a card with a unique barcode on it. They have to scan the card barcode when they get into the office
2. You can use RFID Card. You need to install a scanner and write some code to update NAV database when RFID is reconsigned.
3. You can use cognitive APi service provided my Microsoft https://www.microsoft.com/cognitive-services/en-us/apis and link it in NAV
Answers
Many options,
1. You can give them a card with a unique barcode on it. They have to scan the card barcode when they get into the office
2. You can use RFID Card. You need to install a scanner and write some code to update NAV database when RFID is reconsigned.
3. You can use cognitive APi service provided my Microsoft
https://www.microsoft.com/cognitive-services/en-us/apis and link it in NAV
I hope this helps.