This will work well as long as it's a niche captcha and creating automated solver it's worth the effort. Hardcoding something in JavaScript what will be injecte

This will work well as long as it's a niche captcha and creating automated solver it's worth the effort. Hardcoding something in JavaScript what will be injected to all form submits is even simpler and doesn't require anything from your users. It will work as long as bots don't execute JS or someone is willing to spent some time on modifying the bot.