I have read that there is possible to replace the lucene-version of search with EPiServer Find but I can't find anywhere how to do it.
Are there any documentations on it out there?
You should be able to do this in admin. Admin > Config > Tool Settings > Search Configuration. Uncheck all built-in and keep all that are prefixed with 'Find'.
You may also want to keep 'Jump to' checked.
Thanks, will try that