help making a tf2 inspired scout double jump

ive been wanting to make a tf2 mod pack and i went to make a scout hat that gives you speed and double jump. the speed part is easy but when i looked to make a double jump online all of the online tutorials used blocks i could not find such as "set global variables" i found out how to make a local variable. can someone help me either find these blocks or find another way to make a double jump. (im on the newest version of mcreator.