Unicode Integral symbols codes are (decimal) 8747, 8748, 8749, ..., hexadecimal codes: 222B, 222C, 222D, ...

In FontExpert choose a font having symbols within "Mathematical Operators" Unicode range.

For example, in FontExpert select Cambria Regular font, open

Characters Table view, choose "Mathematical Operators" range from the drop down list, notice integral symbols.

Select a cell with desired symbol, and choose from context (right click) menu one of the commands:

"Copy Symbol to Clipboard" (copies symbol as a text)

"Copy Symbol as Vector Image"

"Copy Symbol as Image..."

and paste it to a third party editor.

If you copy symbol as text, you also must format it with a font having this symbol defined (for example, Cambria Regular).