This article explains how to replace the native search bar in the Blocksy theme by creativethemeshq.
FiboSearch plugin features built-in integration with this theme. It means you can replace the default search bars by selecting a single checkbox. This feature has worked since FiboSearch v1.23.
If you have activated the Blocksy theme or the child theme of Blocksy theme, you should see the following screen in the plugin settings:
Select the option
Replace them and the search bar should be replaced.