The Column() property is mistaken for a function by the Jet expression evaluator. You cannot use it in a query. Instead, you can use =MyCombobox.Column(1) in a text box, and refer to that text box in your query. Better yet, refer to the column directly, meaning outside of the quotes, while building your query. For example:
DoCmd.RunSql "INSERT INTO Table1(Field1) VALUES('" & MyCombobox.Column(1) & "')"
(°v°)