On my last ride I noticed that there was a creaking coming from my carbon fiber forks (or maybe the headset?) when lateral pressure was applied. I first thought it was the handle bars, but was able to hear it by holding the frame and applying lateral force. There wasn't any sound when riding normally, only when rocking the bike.
I have an Easton EC 90 fork, and despite grease, it still creaked, I put in a little synthetic oil from the top, by loosening up the top bolt, and stem, and opening it up about 1/4", letting the oil run down inside, it has not been back since. The fork was installed by a shop mechanic, so, it was not due to bad installation. As I have talked to other riders, who thought the noise was coming from the bottom bracket, like myself, and taken the bottom bracket out several times trying to stop the creaking, it is a common problem. Professionals may have a differing solution for you though.
Actually, I found out what the problem was: The the front wheel wasn't seated properly in the stays. I even tried loosening and re-tightening the quick release and it still did it, so I took it to a bike shop and the mechanic did the same thing and it fixed the problem. I felt stupid, but now I know.🙄
Had same problem...changed the top cap on the aheadset and problem disappeared. The LOOK cap included with fork was soft or cheap...try a Chris King cap. Maybe it'll work for you.