Star Wars has hinted the Sith may be able to capture Force Ghosts. Death is not the end when it comes to the Force, as proven back in 1977 when Obi-Wan Kenobi's voice gave Luke Skywalker guidance during the Death Star run. It didn't take long for Lucas to build on this idea, and in Return of the Jedi viewers caught their first glimpse of Force Ghosts. The spirits of Obi-Wan Kenobi, Master Yoda, and even Anakin Skywalker manifested to celebrate Luke's triumph.
Matt Stover's novelization of Star Wars: Episode III - Revenge of the Sith confirms only light siders can become Force Ghosts. "[Immortality is] the ultimate goal of the Sith," the spirit of Qui-Gon Jinn explained, "yet that can never achieve it. It comes only by the release of self, not the exaltation of self. It comes through compassion, not greed. Love is the answer to the darkness." Such Force Ghosts had generally been seen as neutral observers or mere spirit guides, until Rian Johnson's Star Wars: The Last Jedi. That featured a scene in which Master Yoda's Force Ghost summoned elemental lightning, confirming they can indeed affect the real world. Suddenly Force Ghosts had become a power to be reckoned with.
Star Wars: How The Dark Side Creates WEREWOLVES
George Mann's recently-published Star Wars: Dark Legends subtly hints the ancient Sith had a way to deal with Force Ghosts, however. This is a collection of in-universe myths, although Lucasfilm has stressed every one of them contains a grain of truth. One of these stories, "The Gilded Cage," tells of an ancient, subtle war between the Nightsisters and the Sith Lord Darth Caldoth. The Nightsisters attempt to lure him into a battle with what seems to be a Force Ghost, but he saw through their trick, and prepared a response; he performed a binding ritual that trapped the Force Ghost inside a vial. He stoppered it, and took it away.
It's a fascinating tale, with George Mann clearly lifting the idea from the real-world legend of the genie (another short story in the book introduces werewolves to the Star Wars galaxy too). It suggests the ancient Sith were aware of the existence of Jedi Force Ghosts, and had learned dark rituals that allowed them to trap these beings. Interestingly, "The Gilded Cage" actually suggests this ritual had been stolen from the Nightsisters themselves.
There's no way to know whether Palpatine was aware of this ritual, however. The Jedi had forgotten how to become Force Ghosts over the millennia, with Qui-Gon Jinn learning the technique from the Disciples of the Whills. He passed on his knowledge to others, allowing Master Yoda, Obi-Wan Kenobi, and ultimately even Anakin Skywalker to attain to eternal life within the Force. Given the Sith wouldn't have encountered Jedi Force Ghosts for a long time, it's likely the techniques used to trap them had long since been forgotten as well.
Star Wars: Why George Lucas Replaced Anakin Skywalker's Force Ghost