We have had machines that do what you describe for decades.
Here's Daniel Dennett in Consciousness Explained (1992)
When your eyes dart about in saccades, the muscular contractions that cause the eyeballs to rotate are ballistic actions: Your fixation points are unguided missiles whose trajectories at lift-off determine where and when they will hit ground zero at a new target ...
Amazingly, a computer equipped with an automatic eye-tracker can detect and analyse the lift-off in the first few milliseconds of a saccade, calculate where ground zero will be, and before the saccade is over, erase the word on the screen at ground zero and replace it with a different word of the same length. What do you see? Just the new word, and with no sense at all of anything having been changed. As you peruse the text on the screen, it seems to you for all the world as stable as if the words were carved in marble, but to another person reading the same text over your shoulder (and saccading to a different drummer) the screen is aquiver with changes.
The effect is overpowering. When I first encountered an eye-tracker experiment, and saw how oblivious subjects were (apparently) to the changes flickering on the screen, I asked if I could be a subject. I wanted to see for myself. I was seated at the apparatus, and my head was immobilized by having me bite on a "bite bar". This makes the job easier for the eye-tracker, which bounces an unoticeable beam of light off the lens of the subject's eye, and analyzes the return to detect any motion of the eye. While I waited for the experimenters to turn on the apparatus, I read the text on the screen. I waited, and waited, eager for the trails to begin. I got impatient. "Why dont you turn it on?" I asked. "It is on," they replied.