Find a String in a String chaine

Hi, I need a function that detects if a string was found inside another string:

here’s an example:
string1 = “ABC”
string2 = “FGABCJHG”

in this case, the function would return true…
any ideas on how to make this? i m being lazy, i could try to do it by myself but sometimes this kind of functions were already made by someone and they are in internet or whatever.

thanks!