Cats can hear at the ultrasonic level. The noise of a crinkly paper could mimic the ultrasonic communication of mice, and could even sound similar to the movement of mice, which can trigger prey drive in cats!
Some crinkle noises can even be dangerous for cats, since they can trigger seizures in them. The most common sound that causes seizures in cats is the sound of tin foil crinkling.
The condition of seizures in cats caused by crinkles is called FARS. It’s quite uncommon and affects much older cats starting at the age of 15. Chances of your cat suffering from FARS is quite low.