How can I get my daughter to stop sucking her thumb?

Any of you mamas have a thumb sucker? My daughter is almost 9 months old, she refuses a pacifier and sucks on her thumb religiously. Unfortunately her fingers now are chapped and cracked…how do I fix this? Please help

My youngest daughters always been a thumb sucker. She’ll be 2 in December. She would also never take a soother, she started around 5 months old and I have no advice lol I asked my doctor and she said if it comforts her, leave her alone. So I haven’t tried to stop her, she only does it now when she’s tired or going to sleep. She has also only sucked the one thumb

Thumb guard off Amazon!! Only took 2 weeks of wearing!!