I have a implanon can it make me gain weight?

Yes: Progestin (synthetic Progesterone compounds found in hormonal contraception) can make you gain some weight. Implanon is an example.

Some women do gain : Some women seem to be very susceptible to synthetic hormones and experience weight gain. It is not always clear if it is fluid retention, increased appetite and food cravings or something else. Be careful to eat healthy and exercise to minimize any weight gain and hopefully still benefit from your implanon.