Is there a way to get precise input ?

But what would be the use ot it? Your issue I think is not about checking the input more often but about increasing your FPS. Even if you could check your input every 5ms, the frame rate is still 16ms. So only the last one (or the first one) would be considered. Even if you put 20 letters in the postbox, it is collected once a day. Or I misunderstood.

It's for a musical game. I need very precise input for checking the exact moment (or with a very nice precision) of when the users push a button.

I don't necessary needs to doing something DIRECTLY when the input is raised, but i just need to know the exact or very precise time of when the users push a key.

Actually, i cheat. I force the disable of VSync, set the targetFrameRate to -1. And, even in a 5 years old computer, i get 200 FPS, which is 5ms accuracy, which is pretty good.

But i was asking for a more "clean" solution ?

Yep, i already know it's difficult, and of course i don't expect precision to milliseconds. But 5ms will be fine.

I'm just asking myself how others musical games works, are they got the problem too, or are they doing something else ?

Other musical games cheat, too. They have to. For consoles, they can have the additional problem of latency between a wireless controller and the console. There's also the issue of modern technology like HDTVs and capacitive touchscreens (like on most mobile phones) having performance issues for games with really tight accuracy: http://www.gamasutra.com/view/news/174502/Your_HDTV_killed_PaRappa.php#.UFdIH41lS3Y

Can you not use Get$$anonymous$$ey in FixedUpdate (you would have to handle your own Down/Up notifications because they won't work in FixedUpdate)? Then you'd set your fixed update step to be 200x per second.