Well to start off with look up the word karma. If you did, you'd realize it wasn't dependent on someone seeing you. If it helps, think of it as sin(although karma also covers good actions). Just because nobody saw you steal from a charity box doesnt mean you wont be made to suffer for it later

–noun
1.
Hinduism, Buddhism . action, seen as bringing upon oneself inevitable results, good or bad, either in this life or in a reincarnation: in Hinduism one of the means of reaching Brahman. Compare bhakti ( def. 1 ) , jnana.
2.
Theosophy . the cosmic principle according to which each person is rewarded or punished in one incarnation according to that person's deeds in the previous incarnation.
3.
fate; destiny.
4.
the good or bad emanations felt to be generated by someone or something.