Try this
; drive type 1 is a usb 2 hard disk
(defun UsbDriveSerialNumber ( / fso dr)
(setq fso (vlax-create-object "Scripting.FileSystemObject"))
(vlax-for d (vlax-get fso 'Drives)
(if
(= (Vlax-get d 'DriveType) 2)
(setq dr (cons (list (vla-get-path d) (vla-get-SerialNumber d)) dr)
)
)
)
(vlax-release-object fso)
(reverse dr)
)
(UsbDriveSerialNumber)