The Bible does not explicitly answer this question.
That Moses was chosen and called by God and given power from Him is clear from Exodus 3:10,12; 4:12,15,17; etc. That he was married to a daughter of Jethro, the priest of Midian, is clear from Exodus 3:1 (as Jethro was a man who held divine authority, it is implied that it was under Jethro's authority that Moses entered into the ordinance of marriage).
Although the Bible is not explicit that Moses received an ordination and/or anointing under Jethro's hand in Midian, it is a plausible inference given that:
- Jethro was the spiritual leader of the community
- Moses obtained Jethro's blessing before returning to Egypt (see Exodus 4:18)
Extra-Biblical material teaches that Moses was ordained by Jethro; the Bible itself may imply this, but does not state it directly.