In ESXi 6.5, the legacy USB drivers, including xhci, ehci-hcd, usb-uhci, usb, usb-storage, and so on, are replaced with a single USB driver named vmkusb. The vmkusb driver is loaded by default and it is applied to all the USB Host Controllers (XHCI/EHCI/UHCI/OHCI), USB Keyboard, Mass Storage, and supported USB NIC devices connected to the host.
You can disable the vmkusb driver by running esxcli system module set -m=vmkusb -e=FALSE. The legacy USB drivers are loaded at the next reboot. To re-enable the vmkusb driver, run esxcli system module set -m=vmkusb -e=TRUE, and reboot the host.