Collect performance information on high CPU condition in SQL Server
I think we might need to dip into sys.dm_os_ring_buffers and sys.dm_os_sys_info to get the CPU utilization data.

Please find below the script of Glenn Berry

-- Recent CPU Utilization History (SQL 2008/2008 R2 Only)
DECLARE @ts_now bigint = (SELECT cpu_ticks/(cpu_ticks/ms_ticks)FROM sys.dm_os_sys_info); 

SELECT TOP(144) SQLProcessUtilization AS [SQLServerProcessCPUUtilization], 
               SystemIdle AS [SystemIdleProcess], 
               100 - SystemIdle - SQLProcessUtilization AS [OtherProcessCPUUtilization], 
               DATEADD(ms, -1 * (@ts_now - [timestamp]), GETDATE()) AS [EventTime] 
FROM ( 
      SELECT record.value('(./Record/@id)[1]', 'int') AS record_id, 
            record.value('(./Record/SchedulerMonitorEvent/SystemHealth/SystemIdle)[1]', 'int') 
            AS [SystemIdle], 
            record.value('(./Record/SchedulerMonitorEvent/SystemHealth/ProcessUtilization)[1]', 
            'int') 
            AS [SQLProcessUtilization], [timestamp] 
      FROM ( 
            SELECT [timestamp], CONVERT(xml, record) AS [record] 
            FROM sys.dm_os_ring_buffers 
            WHERE ring_buffer_type = N'RING_BUFFER_SCHEDULER_MONITOR' 
            AND record LIKE '%&lt;SystemHealth&gt;%') AS x 
      ) AS y 
ORDER BY record_id DESC;


Source : Glenn Berry's Script