How to retrieve data from Column where Column name is stored in a variable

Where do you want to execute the code? Template, Script, ...?

I want this code to be executed in script

In a matter of fact, in a script, you cannot use the $-notation so you have to use the methods available at the IEntity object.

In your case, that would be the GetValue method.

Dim myEntity as IEntity
Dim ColumnToFetchAs String
Dim value as String

myEntity = Session.Source.CreateNew("Person")
ColumnToFetch = "InternalName"
value = myEntity.GetValue(ColumnToFetch).String

Please take a look at the ScriptSamples in the SDK on the product delivery for more information. (<OneIM>\Modules\QBM\dvd\AddOn\SDK\ScriptSamples\)