It's not like someone's physically going up to Batman and doing some sort of mind meld on him. They can prey on the mind from wherever they are, think of it like Freddy Krueger invading a nightmare or a witch casting a spell from a cauldron. He does it within the mind, it could literally just be him seeing what is happening on earth and just twisting nightmares in Batman's mind to be even worse than they are. That's not to say you're going to see him just that he can invade the mind from afar.
In Womder Woman's case we know she works with magic, she be showing Bruce a vision of what may happen if he pursues this war with Superman via mystical forces.