The command
c()<Esc>P
Explanation
If you want to put the word under the cursor in to brackets this is viwc()<Esc>P.
viw will visually select all charactrs in a word.
c() will cchange the selection and drops you into insert mode, where you type the literal characters ( ). Also, c automatically copies the original content to your yank buffer (clip board).
With <Esc>P you return Escback from insert to normal mode and Paste the previous content.