if I use Trifarian Captain and play nocturne, can I still draw a card from Trifarian Captain ability?

Yes — banishing and playing Nocturne doesn't eat Trifarian Captain's draw; you still reveal-and-draw a unit or gear from the top 4 that costs 3 or less Energy with Power cost no more than [A].

The technical reason is that Nocturne was never eligible for the Captain's draw anyway — he's 4 Energy, and the Captain only draws a card with Energy cost no more than [3]. So "As you look at or reveal me…" just converts Nocturne from a top-deck card into a unit you play for [A], and the Captain's effect continues: reveal a different qualifying card and draw it, then Recycle the rest. If none of the other three cards qualify, you draw nothing.

One thing to keep in mind: the banish-and-play happens inside the Captain's play effect resolving, so no one gets a Reaction window before Nocturne hits the board (FAQ #12292), and playing him that way still counts as playing a card for triggers like Legion or "second card this turn."