Creating a realistic sticker on a piece of fruit

I would try to get comfortable with just doing good transformations, warping, puppet warping, and maybe even some liquify for subtle tweaks. Once you get the shape right and add some details, it'll look fine. Here's a little 5 minute demo I put together to help you out. The end result being this graphic below. Links to screen recording and master PSD file below in the text.

To get the form right start with the Free Transform box, and change it to Warp using the Warp button in the top menu bar area. It presents itself after you choose Free Transform. In there you can choose some various preset warps, or you can drag the grid around to distort it yourself. I do this a lot for client composites and it works well for me.

Once you've got the shape right, then you can start adding highlights and shadows to add some realism to it.

Here, I've made a quick screen recording of the transformation part. You can download the video here.

Sticker-transform.mov - Google Drive

And if you want to deconstruct the file with lighting and things on it, I've uploaded the PSD file so you can play with it.

Lime-sticker.zip - Google Drive

Good luck!

Have you try a displacement map, im sure this is probably the best technique for what you need. There are very good tutorials in you tube.