@Zuzia :-
Huh. Now that's weird....
I've just run HardInfo myself, and selected 'Input Devices'. There's no rhyme or reason to this at all.
Sleep Button - seen as 'Keyboard'
Power Button - seen as 'Keyboard'.
I've got three mouse dongles permanently plugged-in. Two are normal mice, one is a 'pen mouse', which I use for graphical design stuff.
Both 'normal' mice - seen as 'Mouse'.
Pen mouse - seen as 'Keyboard'.
Speaker - seen as 'Speaker'. However.....
Both my wireless headset AND my Logitech c920 HD Pro webcam are seen AS (yup; you guessed it!).....a 'Keyboard'.
How can a webcam be detected as a keyboard? How can a headset be detected as a keyboard?
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I suspect this is more to do with how the kernel is seeing those devices, and the type of driver that is being assigned to each. Even my old optical, tray-loading DVD/CD combo drive is being seen as a 'Keyboard'.....largely, I suspect, due to the fact that I now run it as an 'external' drive, plugged into a USB 3.0 to SATA adapter.
This is only a guess, but I rather suspect that every device that is being seen as a 'Keyboard' is probably being assigned the same USB root 'hub' driver, irrespective of individual device drivers. This is all about the actual physical connection, I think.....since every one of these devices is using a physical USB type-A connector.
Just my thoughts on the matter, but I don't think there's anything you can do to 're-configure' that classification. I also don't think there's that much you can do to change this behaviour, either; my guess is that your microphone isn't being assigned a dedicated driver by the kernel, and is simply being assigned a 'generic' one instead.
I could of course be completely wrong...! 
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Currently in Slimjet, running in Fossapup64, and I've just performed a couple of Google voice searches, having set the c920 webcam's microphone as the 'default' one for Google.
Works perfectly, for me.....
(*shrug...*)
Mike. 