How to find out what uses cpu other than SQL

Process Monitor from SysInternals will break down every component that is using memory and or CPU. I am sure you could run this and write the counters to a log file. I have only used the GUI of it to track things real time. It is a free tool so check it out.

As @TRAD said i will go with Process Exec too. But if you want to get a snapshot of how SQL vs Non-SQL processes use CPU on your sever using TSQL you can use below queries by Glen Berry:

-- Get CPU Utilization History for last 144 minutes (in one minute intervals)

--  (SQL 2005 Only)
DECLARE @ts_now bigint; 
SET @ts_now = (SELECT cpu_ticks / CONVERT(float, cpu_ticks_in_ms) FROM sys.dm_os_sys_info); 

SELECT TOP(144) SQLProcessUtilization AS [SQL Server Process CPU Utilization], 
               SystemIdle AS [System Idle Process], 
               100 - SystemIdle - SQLProcessUtilization AS [Other Process CPU Utilization], 
               DATEADD(ms, -1 * (@ts_now - [timestamp]), GETDATE()) AS [Event Time] 
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 '%<SystemHealth>%') AS x 
      ) AS y 
ORDER BY record_id DESC OPTION (RECOMPILE);

-- This version works with SQL Server 2008 and SQL Server 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 [SQL Server Process CPU Utilization], 
               SystemIdle AS [System Idle Process], 
               100 - SystemIdle - SQLProcessUtilization AS [Other Process CPU Utilization], 
               DATEADD(ms, -1 * (@ts_now - [timestamp]), GETDATE()) AS [Event Time] 
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 N'%<SystemHealth>%') AS x 
      ) AS y 
ORDER BY record_id DESC OPTION (RECOMPILE);