Judul bab angka Romawi, Caption gambar/tabel angka Arab, how?

Number the chapter headers with Arabic numerals and then use hidden formatting (ctrl+shift+h) to hide the number and manually write "Chapter I", "Chapter II", etc. It's not the prettiest solution, but I think it's the easiest. ToC should use whatever you've written there so you can manually change that too if you need to.

From: In MS word, how can I make caption of an image like "2-1" instead of "II-1" if heading one is numbered under roman numbers? - Super User