Creating a wave

May be you can try to convert this to brush

One way to do it would be with a blend.

1. Draw two lines with a stroke and no fill.
2. 
3. In the Stroke panel, choose the first profile and increase the line weight.
4. 
5. Apply a dashed line.
6. 
7. Choose Object > Blend > Make.
8. Then choose Object > Blend > Options.
9. Change to Specified Steps and turn on Preview.
10. 
11. Only the beginning and ending paths are selectable in a blend, and the blend acts like a group. You can use the direct selection tool to change the shape of the beginning and ending paths, or to change any of the stroke characteristics of the paths.
12. 

Here is just one method  using the envelope distortion option

see here in pdf

https://carvajal-my.sharepoint.com/personal/mario_arizmendi_carvajal_com/_layouts/15/guestaccess.aspx?docid=12b7a71bba90…

Which version of Illustrator are you using?