Actually, you can do that on Steemit itself. The trick is to use the Markdown mode to create the link and then use Editor mode to write text itself.

1. Click "Submit a story"
2. Click the link on "Insert images by dragging & dropping, pasting from the clipboard, or by selecting them."
3. Upload picture from your computer
4. Copy the link from inside the brackets (http......png)
5. Paste the link somewhere outside the Steemit
6. Click "Clear" to get rid of everything from the writing window
7. Click "Editor" to be able to write without using Markdown
8. Paste your saved link anywhere in your tekst

Let me know if it works :)