You write sizzle.
First of all, you are the one who double clicks your mouse. If you are talking about why the mouse makes two clicking sounds when you click it once, that is because it makes one click sound when you depress the mouse button, and it makes another when you lift it up again.
baaah
ting
BOOM!
bacock
"'Pika' is the sound Japanese say an electric spark makes. And 'chu' is the sound a mouse makes." -Satoshi Tajiri, creator of Pokémon
You could write Bzzzz or Zzzz or any other buzzing sort of sound.
The sound a whistle makes is often described as "whoo" or "wee" depending on the pitch and intensity of the sound.
While there is no official name to the sound and noise that a mouse makes, it is generally called a "squeak" based on the squeaky nature of the tone of the sound. These squeaks help a mouse communicate all different sorts of emotion ranging from happiness to sadness to even hunger.
"bzzftt"
dribble dribble