How to indicate there's some info available on hover/click?

1. "Info" icon in the corner:

May be on hover or on click. 

2. Mobile: remember there's no hover. 

3. Highlighting with styling. Example -- dotted underline. Info may appear on hover or on click:

4. 4. Mouse pointer changing on hover:

Then info is displayed on click.

Source: ux.stackexchange,  ux.stackexchange