Even if said enemy jungler flashes/dashes/whatever, you could just chase and keep hitting them. If I want to stop the enemy jungler, I don't have to be Camille. I can be literally anyone with CC or any sort of mobility. They're not going to get to the objective in a timely manner unless they have their team or the jungler is fed enough to oneshot me and keep going.
They would have to pay attention unless they want to just die for free.
You could A, kill her, B, force her out, C, make her leave of her own choice, D, have prepared beforehand with a spellshield, E, use some other way to avoid it (untargetability), or if you have a mobility ability/Flash, use it into your own team (if they're there) to drag Camille's ult into your own team.