FiboSearch plugin has built-in integration with the Open Shop theme. It means you can replace the default search bar by selecting a single checkbox.
If you have activated the Open Shop theme or child theme of Open Shop, you should see the following screen in the plugin settings:
WooCommerce -> FiboSearch -> Starting (tab)
Select the option “Replace the Open Shop search bars with the FiboSearch” and the search bar should be replaced.