Consider not hiding it
While it's often useful to conceal exactly what the die results were, I feel it's not often useful to hide that advantage or disadvantage is happening. When I'm DMing, advantage or disadvantage on a roll is my cue to make that into a story beat -- in other words, I want to play up the fact, not conceal it!
For example, if a monster is searching for the PCs and they don't know it, but the creature is nearly blind, I'm not going to just roll behind my screen and tell them the monster obliviously lumbers past their hiding place; I'm going to describe how they can hear it sniffing deeply, scenting the air as it passes and how it looks right at their barely passable hiding place but then just wanders past as if it didn't even notice.
If the noble the PCs are attempting to con is secretly a con artist himself and gets advantage against them because he knows exactly how a con works, I'm not going to hide that he's rolling with advantage against them. I'm going to describe how the noble's eyes narrow with suspicion as the con unfolds and he seems to know what they're doing almost before they do it.
Rather than trying to hide metagame information, I push that information out of the meta and into the narrative. If the players are asking "Wait, why did you roll two dice?", the characters should be saying "That was strange, did you notice that?"