Microsoft Whiteboard can be added as a tab to a Teams channel.

Add a whiteboard the same way you’d add most tabs:

1. Click + (Add a tab).
2. Select Whiteboard either from the choices presented or by entering Whiteboard in the Search box.
3. Name your Whiteboard and click Save.
4. A new tab will appear at the top of the channel window that can be used to get to the whiteboard. 

Whiteboard functionality is available directly in Teams, and for more intensive use, like drawing or writing with a stylus or pencil on iPads or Windows tablets, you can open your board in the Whiteboard app available in Apple's, Microsoft's, and Google's app stores. Your whiteboards can be found on the web at whiteboard.microsoft.com. Learn more about Microsoft Whiteboard.