High MySQL CPU usage but no heavy query


When I run “top” command on my Linux it shows that MySQL is taking 400%-500% CPU usage. But when I run 'watch mysqladmin pr" command to see a list of queries being run by MySQL then it shows just 2, 3 queries and that too only taking 2, 3 seconds. The “top” command shows MySQL constantly fluctuating CPU usage like 130%, 200%, 340%, 230%, 400%, 440%, 635%, 335% e.t.c. but “watch mysqladmin pr” command is not showing queries that are taking up CPU usage. How do I check why MySQL is using so much CPU?