Hi Deepak,
I am Sumit, an Independent Advisor here to assist you.
Likely a scan in the background is running.
Are you using another antivirus program?
https://www.techcrises.com/windows-10/msmpeng-e...
https://www.widgetbox.com/msmpeng-exe-high-cpu/
Standard 3rd party link disclaimer:
There may be links to non-Microsoft websites that would provide accurate and safe information. Watch out for ads on the websites which are frequently classified as a PUP (Potentially Unwanted Products). There is no need to buy paid products to fix your computers as they do more harm than good sometimes.