I want to create a VOK learning survey using Likert

I'm not a native English speaker: what is VOK?

You can use either custom Likert questions or use the MCQ type of questions to create Likert questions that need reporting in some way. Have a look at this post:

Graded Survey? - Captivate blog

For custom Likert questions use the radiobuttons Learning interaction to simulate the style of Likert questions. You can have multiple instances of that interaction on one slide, and each chose radiobutton can be stored in a user variable.

Likert questions in Captivate have no score.  They don't calculate anything.

If you want to create something that assigns a value to each choice the user makes, you need to either use interactive objects such as buttons or Smart Shapes that the user can click, or else use Learning Interactions that allow variables to accept values from the user's selections. Then you can do math with Advanced Actions to calculate the results.