I read this story about a device that lights up or buzzes or does something moments before it you press a button or something, effectively killing the notion of free will. I read the recently, online, but it could have been floating around for a longer time.
You couldn't outwit the device no matter how hard you tried. You could pretend you are going to press and not press but it won't light up/buzz. You accidentally press it and it would buzz/light up just before. The story was more like an essay, like how a news article would read. I don't remember the ending. I found it while browsing through a few Hugo-award winning writers' short stories, though not sure who.
I also remember a part where people go mad trying to outwit the device into not knowing what they will do. But no matter how random they are, it always knows because there is no such thing as free will.
I remembered one more piece of information. Someone reaches out to the present from the future — not sure why. It end's with a line something like "because I had to."
I have searched for stories of free will and it shows a lot of things, but not this story. I have tried device and free will in the same search to no avail.