You can use lists() method for getting ids. Let your model name be ‘Test’.

Test::where('id' ,'>' ,0)->lists ('id')->toArray();

You can use the get() method also.

test::where('id' ,'>' ,0)->get('id');

For Laravel versions above 5.2

Pluck() method can be used instead of lists(),because lists() is deprecated.

To get the related ids lists through a many to many relationships. You can use DB class

 example:

DB::table('name_of_table')->where('condition')->lists('id');