"When we saw Adam, all we could think of was a young David McCallum," executive producer Gary Glasberg said in a statement. "We can't wait to introduce him as young Ducky and watch what he brings to this unusual role."
In the episode, which is scheduled to air in October, fans will learn about Ducky's past relationships and also learn why he has a penchant for bow ties.
Campbell previously played Cal Vandeusen on "Harper's Island."
"NCIS" kicks of Season 12 Tuesday, Sept. 23 on CBS.
Are you looking forward to meeting Young Ducky?