scketch in scketch

Know any a way to do a scketch in a schetch?

No, but you can have a separate function that runs when a button press is detected.

start of loop
  if button1 is pressed
    call functionX
  end of if
end of loop

functionX
  do stuff here
  either stay in the function
  or return to where it was called
end of function

What is it that you are trying to do ?