Teenage wicketkeeper-batter James Rew, who recently passed 1,000 Championship runs for the season, will serve as Dickson's vice-captain
Somerset have signed Ireland international Curtis Campher for their 2023 One-Day Cup campaign.
The 24-year-old will be available for their first five matches before linking up with the Ireland squad ahead of the home white-ball series against India.
The allrounder has made 49 List A appearances across his career, scoring 1,146 runs at 30.97 (one century, eight half-centuries) and taking 45 wickets with an economy of 5.47. 30 of those appearances have come on the international stage for Ireland.
Campher is tasked with filling the shoes of Ben Green, who received a wildcard contract for Welsh Fire in The Hundred after his impressive performances in the T20 Blast.
Sean Dickson (left) will captain Somerset as they attempt to win a second white-ball trophy in 2023 [Harry Trump/Getty Images]
On signing for Somerset, Campher said: "Playing in England is something that I've wanted to do for a while and I'm looking forward to challenging myself over the next few weeks.
"Obviously, Somerset have just won the Vitality Blast and it would be incredible to help play a part in the club clinching more silverware this summer."
At Somerset, Campher will be captained by Sean Dickson. The batter joined Somerset on a three-year deal ahead of the 2023 season and has scored 1,403 runs at 29.85 in 57 List A matches.
Teenage wicketkeeper-batter James Rew will serve as his deputy.
"The offer took me by surprise, but it's a really exciting opportunity," Dickson said. "It's an absolute honour and privilege to lead this group, and hopefully we can bring some more silverware home this year.
"We've got an exciting young squad and I'm looking forward to seeing them flourish under pressure."
James Rew has been appointed Somerset vice-captain at 19 [Harry Trump/Getty Images]
One-Day Cup head coach, Paul Tweddle, added: "Sean has a lot of respect within the dressing room due to how he has performed in his career so far. He's held in very high regard by the squad, and he has an outstanding cricketing brain. He has a good record in the format and was an integral element of the Durham side that reached the final in 2021.
"We saw on Finals Day that he is a big game player, and he stood up when we needed him. His credentials as a white-ball cricketer are proven and I feel that he is the ideal fit for the role.
"James is one of those players who we saw first and foremost in the One-Day Cup, and this will give him the opportunity to broaden his experiences. Although he's a young player, he is a senior voice within the dressing room.
"He's already played a lot of big games and has played a lot of cricket for someone who's still only 19. We've got a lot of young players in the squad and we feel that it's important that they have someone of a similar age available to talk to."