For live work, use a lapel mic inside the drum. The clayton Udu drums are equipped for this by providing a small hole in the neck of the drum. I recommend something like the Countryman Cardioid lapel.
For studio work, use the lapel and/or a large diaphragm condenser mic, such as the AKG 414, to mic the outside of the Udu.
Both of these mic techniques work well, and I've used combinations of the two in the studio. For live stuff, you really need to mic the Udu internally.