How can I add small annotation-like text (superscript)?

Wondering how I can make text appear to be small and float at the top kind of like an annotation. Pretty much exactly like this website is doing:

http://www.peiliew.com/

Have been looking around but couldn't find anything.

Thanks!

Paul's answer works well. In addition, if it's something you use often and require the style to be in-line with the rest of your text, I've created a plugin for Squarespace that allows for superscript, subscript and more. See Squint.

-Brandon
Project Mgr. and Developer at Ignertia
Creator of Squint - Custom Text Styles & Headings for the Squarespace Text Editor

I do it like so … (for digits)

1. I select the digit that I would like to superscript
2. In MacOS, I launch the Character Viewer
3. I use the search function available in the Character Viewer window and search for superscript
4. From the search results, I double click the character I want to replace the selection I made in step 1 and the selected text is now replaced by what I double clicked on

As a tip, you can pretty much double click on most anything inside the character viewer and it will "type" into the text block. I might be worth your while to inspect the element using the browser inspector to learn what is going on behind the scenes as it were. I would also test the results by viewing the contents in a variety of browsers to understand any limitations that might not be obvious.

There are Unicode superscript characters.

Superscript: ᴬᴮᶜᴰᴱᶠᴳᴴᴵᴶᴷᴸᴹᴺᴼᴾᵠᴿˢᵀᵁⱽᵠˣʸᶻᵃᵇᶜᵈᵉᶠᵍʰᶦʲᵏˡᵐⁿᵒᵖᵠʳˢᵗᵘᵛᵠˣʸᶻ¹²³⁴⁵⁶⁷⁸⁹⁰

Subscript: ₐBCDₑFGₕᵢⱼₖₗₘₙₒₚQᵣₛₜᵤᵥQₓYZₐᵦ𝒸𝒹ₑ𝒻𝓰ₕᵢⱼₖₗₘₙₒₚᵩᵣₛₜᵤᵥᵩₓᵧ𝓏₁₂₃₄₅₆₇₈₉₀

You can copy these characters and paste them.

You can also use this website which converts some letters, numbers & glyphs into superscript:
https://lingojam.com/SuperscriptGenerator