Yes. Go to Search (grainge.org) and what you are seeing there is ZoomSearch operating across the original part of my site. That is created in Dreamweaver but it can be integrated into RoboHelp Classic for sure. As above, I think it should also work on the new UI versions but I haven't tested it.
Ignore the appearance of the page as you can configure that how you want. Zoomsearch creates a small number of files and it is those I think your developers could integrate into whatever they are building. It's not free but the price is not high.
I am not saying for sure it will do what you want but your developers can determine that.
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My site www.grainge.org includes many free Authoring and RoboHelp resources that may be of help.