Do you mean all of the beeps, etc.? Probably a softsynth of some type. Spectrasonics Omnisphere, Native Instruments, Cycling '74 Max and Arturia are popular with film sound designers, and many DAWs come with softsynths of various flavors. And, of course, there are lots of hardware synths as well, plus numerous sound FX libraries.
freesound.org
'cmon dude.. did you even try searching in freesound.org? search for "beep" yields over a 1000 hits..
sorry bro, didnt mean to come off as jerk.
Do you have any audio editing software? Mixing sounds together, using filters and the like is the fun part of sfx. Speeding up a sound can really change its effect. Try looking for sounds that are NOT what your looking for Like vacuum cleaner start up.. etc.. might SOUND more like what you want..