One interesting technique is that of the dream state yogas. To practise them we should realize that we are dreaming, and then engage a certain practice deliberately. Because our mind has become already more subtle, then with little effort a still deeper state of Consciousness can be utilized.
When we do that we can develop a dream body. This special dream body is something separate from our physical body. It is a subtle body, and it can go many places and do many things.
I think this body is the best secret agent. Equipped with this technique, one can fulfill one's responsibilities. There is no danger in getting caught. Nobody else can see one's dream body.
This type of practice deals mainly with gaining control over the subtle body and subtle mind. That comes in tantric practice.
Excerpted from "Cultivating a Daily Meditation" by the 14th Dalai Lama