Dear Abhijit,

what thickness range  do you expect?

Please see for example the links.

https://arxiv.org/pdf/0812.0690.pdf

https://www.ncbi.nlm.nih.gov/pubmed/26894444

http://www.univie.ac.at/asem/Graz_MC_09/papers/45505.pdf

Article Accurate thickness measurement of graphene

Thanks Gerhard Martens sir

You can use AFM to measure thickness with maximum accuracy.

As dr.Rahim Abdur commented,AFM is a suitable tool measure accurate thickness of graphene.Beside thickness ,you can calculate number of graphene layers

Number of layers = Total thickness obtained from AFM /thickness of  single layer of graphene

Thanks Dr Rahim Abdur and Prof Hassan Alshamsi 

You can  use transmission plot by considering maxima and minima if your substrate is glass. But if your substrate is silicon or else then spectroscopic Ellipsometry technique should be used.