Use this handy query to find all agent jobs that have steps containing a search string.
DECLARE @Search varchar(255) SET @Search='usp_YourStoredProc' SELECT j.name, j.enabled, s.step_id, s.database_name, s.subsystem, s.command FROM msdb.dbo.sysjobsteps s INNER JOIN msdb.dbo.sysjobs j ON s.job_id = j.job_id WHERE command LIKE '%'+@Search+'%' ORDER BY 1, 3
Thanks to this StackOverflow post for pointing me in the right direction.