if u want it to be undetected then u have to make it your own.
not necessary to code from scratch.
just take public source for example teamgamerfood
compile it get the current dll and save it somewhere
and then add some feature that is not currently in the hack like damage indicator or fake lag
after that compile once again with different name
now go look for a tool called "sigbench" compare both of the dll make sure that the difference is +- 30% or above. then it is undetectable by VAC at least
my cheat was last compiled in january 2018 and still undetected till this moment.