WhatsApp, as it is operated by the same company, uses the same methods as Facebook for this type of information: the Open Graph format. The good thing is: you are already using this on your website. The og:image is also specified here. Unfortunately, I cannot see which plugin you use to add this information to your page.
Facebook has a debugger for Open Graph where you can see that an image is displayed there. would:
https://developers.facebook.com/tools/debug/?q=https%3A%2F%2Fzimbabweantisanctionsmovement.org%2F%25F0%259D%2597%259F%25F0%259D%2597%2598%25F0%259D%2597%259A%25F0%259D%2597%2594%25F0%259D%2597%259F-%25F0%259D%2 597%25A6%25F0%259D%2597%25A2%25F0%259D%2597%259F%25F0%259D%2597%25A8%25F0%259D%2597%25A7%25F0%259D%2597%259C%25F0%259D%2597%25A2%25F0%259D%2597%25A1-%25F0%259D%2597%25A7%25F0%259D%2597%25A2-%25F0%259D%2597%25A7%2F
The strange characters in the URL result from the different character set you are using for the titles as well as URLs. Normally this shouldn’t be a problem – it doesn’t seem to be for Facebook. I can’t judge how WhatsApp handles this.
So take a look to see if your image meets WhatsApp’s conditions: https://developers.facebook.com/docs/whatsapp/link-previews/