i did not write ,release music for some stranger to sample , steal without my permission

i overheard online that it happens alot when thieves steal small artists music - and for me ,i am an struggling unknown songwriter who write music professionally and i do not allow some thief or stranger to use my music for sampling, or steal it without my permission. That is why i copyright all my songs and publish them with BMI broadcast music inc before releasing them or sending it to professional music people. Still i have to careful