If I may ask in here. What is a Yubikey?
A YubiKey is a One-Time Password (OTP) generator device. It generates a unique sequence of characters as an OTP every time its button is pressed. As the term suggests, a One-Time Password is valid only for a single use and cannot be used again for authentication.
Its a secured form of authentication and can be used to be hardware ID bound as well. So only one person can use it and cannot be shared at all. This is unless they share their yubi key