How to add certain heading on table of contents ?. Ex: heading 4 only or heading 2 and heading 3
Built-in controls in TOC generation dialog allows you to limit TOC content to a maximum level, i.e. if you choose 4, Heading 1 to Heading 4 are included. You can’t with the built-ins select only level 4 or omit initial levels.
In your Heading 4 example, if levels 1-3 will never be part of any TOC, there is a dirty workaround with custom paragraph styles permitting to keep the appearance of chapter numbering in the text and ito insert only the target levels in the TOC. Once again, only if levels 1-3 never take part in any TOC.
If this is the same as your need, I’ll explain the dirty trick in an answer.
@ajlittoz Please go ahead an post your “dirty work-around”! Should be interesting. 
(And include the info in the comment, of course, which is the basic answer!)
It’s quite easy. Just disable generation of the ToC from the outline, and explicitly define styles used in the ToC in [x] Additional styles▸Assign styles....
@mikekaganski’s answer pointed me to reconsider my workarounds which where the only possibilities in pre-6.x versions. The current TOC controls in Insert>TOC & Index>TOC, Index & Bibliography make it much easier to build “selective” TOCs. Follow his suggestion, it is the right answer.