A USB token for digital signature is a digital certificate in a password-protected device in its physical form, wherein a personal identity is established. It enhances digital security by proving the identity of the user in electronic form.

Note:
The Zoho Sign USB Signer app on Windows allows users to digitally sign documents using their digital signature via USB drives. The major difference between the Zoho Sign USB Signer app and the Zoho Sign web app (and other mobile apps) is that Zoho Sign USB Signer enables the user to use their personal or organizational digital signature to sign documents from a physical USB device.
You can install Zoho Sign for Windows here.

We can use the USB Signer app for the following processes
Signing documents yourself
Note: Do not proceed to sign the document in the web browser if you wish to sign using your USB token DSC.Signing documents sent to you by others
Note: The Zoho Sign Windows app can only be used for signing documents. To send documents for signature, use the web app or other mobile apps.