Zoom Climbs are also known as an Unloaded G climb or a "0" G Climb, you have speed initially built up possibly from diving in on an opponent. You want to regain as much alt as possible in the quickest and shortest amount of time, pull nose high above horizon roughly 40 degree to 70 degree ( can be more or less, this is just a general suggestion 40 to 70 )
then either let go of the stick to unload your G's. this will let the G's drop back to the regular noticable +1 G( no more elevator input, very little aileron input to keep wings level if needed ) or you can even use a slight push forward on the stick to rest the G meter on ZERO ( no + or - G's ) as you top out you will also be leveling off,
test it in the TA or offline....and compare the differences in how fast you can gain altitude
-climbing while holding stick with a steady pull or pressure on the stick
-climbing after pulling to roughly 60 degree nose up, then unloading ( let go of stick )
-climbing, pulling nose high 60 to 70 degree and using a NO G zoom climb, resting the G meter on zero...........
the difference in altitude gained is quickly and easily noticed
hope this helps