does a (strange unnamed) device appear in the lsusb listing at all, if you plug in just the mic? sometimes there is just an entry missing in the kernel id table and it can't print a name. it should always print the id and the device type, if not, the mic is not recognized as a valid usb device at all.

are mic and headphone one physical device? if so, the mic could 'hide' inside the headphone, i.e. the headphone device is bidirectional.