Code for search bar in the header of websites

Hello everyone, 

I am looking for codes that we can put search bar into our website's header. Also, the search bar provided by square space is kind of slow. Is there any alternatives for search bar? 

Thanks, 

Try this guide: https://www.will-myers.com/articles/adding-a-search-bar-to-your-header-in-squarespace-71

I usually use 3rd party search plugin. But it won't work site wide which will work specifically on each page style.