Utility back Dagger has made the switch from Warrington Wolves on a three-year deal and at 18 years of age the talented youngster is expected to have a bright future ahead of him.
Meanwhile, 19-year-old Williams joins on a one-year deal from Salford Red Devils where the back enjoyed a spell under the Australian tactician back in 2006.
Sheens has been delighted with the recruitment of the pair and is looking forward to seeing them progress at the club next term.
He told the club's official website: “We’re really pleased to bring two promising young players into the club to complement those here who have already come through the City of Hull Academy.
“Connor is somebody I know well from our time at Salford. He can cover two or three positions in the outside backs and is really looking forward to his opportunity here. He’s experienced Super League already and was probably a bit unfortunate not to have had more game time over there, so we’re looking forward to adding him to our squad.
“Will is a current England Academy international who’s got a lot of potential. Again, he’s already had first-team experience and we see a lot of ability in him. Both lads are only young and alongside the likes of Will Oakes, Joe Wardill and Joe Cator, it bodes well for the future of the club moving forward.”