I saw a ghost. Would it be okay to ask psychic who it was?
No. The Church forbids recourse to psychics. The Catechism of the Catholic Church states:
All forms of divination are to be rejected: recourse to Satan or demons, conjuring up the dead or other practices falsely supposed to “unveil” the future. Consulting horoscopes, astrology, palm reading, interpretation of omens and lots, the phenomena of clairvoyance, and recourse to mediums all conceal a desire for power over time, history, and, in the last analysis, other human beings, as well as a wish to conciliate hidden powers. They contradict the honor, respect, and loving fear that we owe to God alone (CCC 2116).
For more information about ghosts and psychics, I recommend a booklet I wrote, 20 Answers: Witchcraft & the Occult.